This invention relates to door sill assemblies and, in particular, to sill assemblies having an adjustable threshold.
Over the years, a wide variety of door sill assemblies have been made with adjustable thresholds. Door sill assemblies initially designed to fit immediately below an entryway door are now often extended to adjacent side lights to provide a continuous sill having a uniform, aesthetic appearance while forming a water tight injunction between the sill and the adjoining building floor surface.
Adjustable sills were developed to provide a threshold which an installer can adjust to fit a specific door. By maintaining a predetermined clearance between the threshold and the door, a door seal can effectively keep out wind and water. It is desirable that adjustable thresholds be easy to install and adjust, structurally sound, relatively inexpensive and aesthetically pleasing. Another important feature in cold climates is that the threshold should provide a good thermal barrier in order to prevent condensation and icing on the portion of the threshold within the building interior.
Accordingly, the door sill assembly having an adjustable threshold, is provided including three main components; an elongated frame member, an adjustable threshold rail positionable relative to the frame member and a plastic threshold cap sized to fit over the threshold rail and to cooperate with frame member to provide for a limited vertical adjustment of the threshold rail and cap. The elongate frame member is made up of a downwardly sloped sill portion, a vertically extending rib portion and a shelf portion located inboard and below the vertically extended rib. The threshold rail is an elongated rigid member having at least two spaced apart feet cooperating with the rail shelf portion. The plastic threshold cap securely fits over the threshold rail and is provided with a pair of downwardly spaced extending ribs sized to securely fit over the vertical rib of the frame member to enable vertical adjustment of the threshold cap and threshold rail in response to positioning the adjustable feet. Preferably, the interior trim molding is provided extending the length of the frame member fixed relative thereto cooperating with the skirt portion of the threshold cap.
In one embodiment, the plastic threshold cap is provided with a series of apertures oriented adjacent the adjustable feet in the threshold rail so that the threshold may be adjusted while installed in the frame. In an alternate embodiment the plastic threshold cap has a contiguous upper surface in which the adjustable feet of the elongate of the threshold rail assembly are adjusted by the installer with the threshold cap and rail assembly removed from the frame member.
A preferred threshold rail assembly is made up of an aluminum extrusion having a generally H-shaped cross section formed by a pair of vertical sides and a horizontal web extending therebetween. The horizontal web of the rail assembly is provided with a series of apertures sized to receive threaded fasteners forming the adjustable feet. The thread fasteners preferably engage a nut sized to fit below the H-shaped web without rotation having a threaded internal bore for receiving a threaded screw which projects vertically through the apertures in the web.